Transform attribute names to proper casing

[gpoitch]

Makes sure attributes are converted to their proper casing when rendering to string. There was a similar attempt with #55 but it was never completed. Reviving it particularly because Safari is excessively downloading an img's src upon hydration due to srcSet casing mismatch between preact/preact-render-to-string. This also adds better support for attributes specific to SVG/RSS/XML.

Incorporated the concerns from the comments in the other attempts/issues.

Attribute list reference: https://developer.mozilla.org/en-US/docs/Web/HTML/Attributes React reference: https://github.com/facebook/react/blob/main/packages/react-dom/src/shared/possibleStandardNames.js

Closes #55 Closes #18

[marvinhagemeister]

@gpoitch I think it's definitely something we should address. Regarding the closing: Did you ran into problems with this PR? I'm mainly curious to see if there is a way without changing the casing in the JSX renderer, but lowercase it in the default mode.

[gpoitch]

@marvinhagemeister accidental auto-close referencing this PR in a private repo. Not familiar with default vs jsx mode - I'll have to read the source code more and circle back.

[gpoitch]

@marvinhagemeister I updated it so the jsx renderer is unaffected by applying the normalization after the attribute hook intercepts the standard rendering.

[changeset-bot[bot]]

🦋 Changeset detected

Latest commit: 61cd8c28f1bd014c5f8dd7cae0167793dd62c166

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
preact-render-to-string	Patch

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